Cleaning Pad Having Preferred Construction

ABSTRACT

A cleaning pad for absorbing liquids from a hard, target surface. The cleaning pad has a hydrophobic floor sheet, and a core joined to the floor sheet. The core has absorbent gelling material therein with a gradient distribution, so that the pad has a particular minimum absorbency as used with water or with common amine oxide cleaning solution. A hydrophilic smoothing strip is joined to the outwardly facing surface of said floor sheet. The cleaning pad provides both good absorbency and a coefficient of friction falling within a specified range judged advantageous for cleaning. The absorbency and coefficient of friction work well with both water and an amine oxide cleaning solution.

FIELD OF THE INVENTION

The present invention relates to a cleaning pad and more particularly toa cleaning pad suitable for absorbing liquid from a hard surface.

BACKGROUND OF THE INVENTION

Attempts have been made in the art to provide cleaning pads which absorbliquids, such as cleaning solutions. The liquids may be absorbed fromhard surfaces, such as floors, tables and countertops. Relevant attemptsin the art include US 2003/0300991, 2004/0074520, 2011/0041274, U.S.Pat. Nos. 6,003,191, 6,048,123, 6,245,413, 6,601,261, 6,681,434,6,701,567, 6,996,871, 7,037,569, 7,096,531, 7,163,349, 7,480,956,7,458,128, 7,624,468, 8,341,797 and 8,707,505, WO200241746.

But hydrophobic floors, such as wood floors having aluminum oxidecoatings, are difficult to clean. Dark color floors and shiny floors arehard to clean, particularly if consumers do not use enough cleaningsolution. If the consumer uses too much cleaning solution, not all of itmay be absorbed and retained by the sheet during cleaning Impropercleaning may be caused by the coefficient of friction between thecleaning pad and surface being too low, and gliding over debris or beingtoo great, and making cleaning difficult to manually accomplish. Someprior art attempts looked at individual materials and individualcomponents of the cleaning pad, but did not consider how all of thesework together to affect cleaning performance. The present inventionovercomes these problems.

SUMMARY OF THE INVENTION

In one embodiment the cleaning pad comprises a pad having a floor sheet,and a core joined to the floor sheet. The core has absorbent gellingmaterial (AGM) therein, so that the pad has a particular minimumabsorbency as used with water or with common cleaning solutions. In arelated embodiment, the cleaning pad may have a coefficient of frictionfalling within a specified range judged advantageous for cleaning.

In one embodiment the cleaning pad comprises a hydrophobic floor sheethaving an inwardly facing surface and an outwardly facing surfaceopposed thereto. An absorbent core is joined to the inwardly facingsurface of the floor sheet. A hydrophilic smoothing strip is joined tothe outwardly facing surface of said floor sheet.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A to a top perspective view an exemplary cleaning pad according tothe present invention shown partially in cutaway.

FIG. 1B is a bottom plan view of the cleaning pad of FIG. 1A, shownpartially in cutaway and having one attachment strip truncated forclarity.

FIG. 2 is a schematic, vertical sectional view taken along lines 2-2 ofFIG. 1B.

FIGS. 3A-3D are graphical representations of the generally proportionaterelationship between coefficient of friction with water and absorbencyof water.

FIGS. 4A-4F are graphical representations of the generally proportionaterelationship between coefficient of friction with a representative amineoxide cleaning solution and absorbency of the amine oxide cleaningsolution.

FIG. 5 is a schematic representation of the floor and stroke patternused for the absorbency test.

FIG. 6 is a perspective view of a cleaning implement usable with thecleaning pad of the present invention and showing the cleaning pad inposition to be removably attached to the cleaning implement.

DETAILED DESCRIPTION OF THE INVENTION

Referring to FIGS. 1A, 1B and 2, the cleaning pad (10) of the presentinvention may comprise plural layers, to provide for absorption andstorage of cleaning fluid and other liquids deposited on the targetsurface. The target surface will be described herein as a floor,although one of skill will recognize the invention is not so limited.The target surface can be any hard surface, such as a table orcountertop, from which it is desired to absorb and retain liquids suchas spill, cleaning solutions, etc.

The cleaning pad (10) may comprise a liquid pervious floor sheet (14)which contacts the floor during cleaning and preferably provides adesired coefficient of friction during cleaning. An absorbent core (16),preferably comprising AGM (16A) is disposed on, and optionally joined toan inwardly facing surface of the floor sheet (14). A smoothing strip(12) may be disposed on the outwardly facing surface of the floor sheet(14). Optionally, a back sheet (18) may be joined to the core (16)opposite the floor sheet (14), to provide for attachment of the cleaningpad (10) to an implement (30). The back sheet (18) may have an outwardlyfacing surface with one or more attachment strips (20) to particularlyfacilitate attachment to an implement (30). The cleaning pad (10) may begenerally planar and define an XY plane and associated X, Y axes. The Zaxis is perpendicular thereto and generally vertical when the cleaningpad (10) is in use on a floor.

If desired, the core (16) may comprise AGM (16A) to increase theabsorbent capacity of the cleaning pad (10). The AGM (16A) may be in theform of particles may be distributed within the cleaning pad (10) insuch a manner to avoid rapid absorbency and absorb fluids slowly, toprovide for the most effective use of the cleaning pad (10). The AGM(16A) also entraps dirty liquid absorbed from the floor, preventingredeposition. If desired foam absorbent material or fibrous material maybe incorporated into the core (16).

Examining the cleaning pad (10) in more detail, the cleaning pad (10)may comprise plural layers disposed in a laminate. The lowest, ordownwardly facing outer layer, may comprise apertures to allow fortransmission of liquid therethrough and to promote the scrubbing of thetarget surface. One, two or more core (16) layers may provide forstorage of the liquids, and may comprise the absorbent gellingmaterials. The cleaning pad (10) may have an absorbent capacity of atleast 10, 15, or 20 grams of cleaning solution per gram of dry cleaningpad (10), as set forth in commonly assigned U.S. Pat. Nos. 6,003,191 and6,601,261.

The optional top, or upwardly facing layer, is a back sheet (18), andmay be liquid impervious in order to minimize loss of absorbed fluidsand to protect the user's hand if the cleaning pad (10) is used withoutan implement (30). The top layer may further provide for releasableattachment of the cleaning pad (10) to a cleaning implement (30). Thetop layer may be made of a polyolefinic film, such as LDPE. A suitableback sheet (18) comprises a PE/PP film having a basis weight of 10 to 30gsm.

Attached to the back sheet (18) may be one or more optional attachmentstrips (20). The attachment strips (20) may comprise adhesive,preferably pressure sensitive adhesive, or may loops for removableattachment to complementary hooks on an implement (30). Suitable loopattachment strips (20) may comprise a laminate of PE film and Nylonloops.

The back sheet (18) and floor sheet (14) may be peripherally joined, asis known in the art. This arrangement creates a pocket for securelyholding the core (16). The core (16) may be juxtaposed with, andoptionally joined to the respective inwardly facing surfaces of thefloor sheet (14) and back sheet (18).

The core (16) may comprise a single layer or two or more layers. Ifplural layers are selected for the core (16), the width of the layersmay decrease as the floor sheet (14) is approached, as shown. The core(16) may comprise airlaid cellulose and optionally polymer fiber, asavailable from Glatfelter of York, Pa. If two airlaid cellulose core(16) layers are selected, each layer of the core (16) may have a basisweight of at least about 75, 100, 125, 150, 175, 200, or 225 gsm andless than about 300 gsm.

Preferably each layer of the core (16) comprises AGM (16A). The AGM(16A) may absorb at least 10, 15 or 20 times its own weight. The AGM(16A) may be blown into the airlaid core (16) layer during manufactureas is known in the art. Suitable AGM (16A) is available as Z3070G fromEvonik of Essen, Germany. Arlaid material containing a gradient AGM(16A) distribution is available from Glatfelter of York, Pa.

The gradient distribution AGM (16A) may be achieved by using more thanone forming head. For example, an airfelt/AGM (16A) line may have threeforming heads. The first head may distribute a relatively large amountof AGM (16A) relative to the cellulose distributed from that head. Thesecond forming head may distribute a less amount of AGM (16A) relativeto the cellulose base, with this mixture being laid onto top of thefirst AGM (16A)/cellulose base. This pattern may be repeated using asmany forming heads as desired. If desired the final forming head maydistribute pure cellulose and no AGM (16A). Generally the layer fromeach forming head does not intermix with adjacent layers. Adhesivebonding and/or thermal bonding may hold superposed layers in place andprovide structural rigidity.

Suitable core (16) layers and a suitable apparatus and process formaking one or more layers of a core (16) having a gradient AGM (16A)distribution are found in U.S. Pat. No. 8,603,622 issued Dec. 10, 2013.The teachings of U.S. Pat. No. 8,603,622 are incorporated herein byreference at column 5, lines 8-14 for the teaching of a suitable core(16) layer and at FIGS. 5-6, with the accompanying discussion at column16, line 41 to column 17, line 59 for the teaching of production devicessuitable to make a core (16) layer for the present invention.

If two airlaid cellulose core (16) layers are selected, the lower corelayer (16L), juxtaposed with the floor sheet (14), may comprise about 10to 20 weight percent AGM (16A), with about 15 percent being foundsuitable. The upper core layer (16U), juxtaposed with the optional backsheet (18), if any, may comprise about 20 to about 30 weight percent AGM(16A), with about 25 percent being found suitable. The total core (16),with all layers thereof considered, may comprise 5 to 50 w %, or 10 to45 w % AGM (16A), the amount and gradient distribution of AGM (16A)being found helpful for the present invention. The percentage of AGM(16A), as described and claimed herein refers to the weight percentageof AGM (16A) in that particular core (16) layer (16U or 16L), withoutregard to the floor sheet (14), back sheet (18), smoothing strip (12) orattachment strips (20).

Each core layer (16L, 16U) and particularly the upper core layer (16U)may be further stratified to provide greater absorbency benefit. Theupper core layer (16U) may have three strata, as formed. The strata maycomprise 0, 25, and 50 weight percent, monotonically increasing as theback sheet (18), if any, is approached, to provide a gradientdistribution.

Generally it is desired that the upper core layer (16U) comprise moreAGM (16A), on both an absolute basis and a weight percentage basis thanthe lower core layer (16L). The arrangement provides the benefit thatgel blocking in the lower core layer (16L) does not prevent fullabsorption of liquid from the target surface and that liquids aretransported upwardly and away from the floor sheet (14).

Any arrangement that provides more AGM (16A), preferably on an absolutebasis or optionally on a weight percentage basis is suitable.Alternatively, either core (16) layer or a single core (16) layer mayhave increasing AGM (16A) concentration in the Z direction.

Any such process, as is known in the art, or arrangement, which providesfor increasing AGM (16A) in the Z direction as the back sheet (18) isapproached is herein considered an AGM (16A) gradient. It is to berecognized that the AGM (16A) gradient may be smooth, comprise one ormore stepwise increments or any combination thereof.

The floor sheet (14) may comprise a discrete apertured nonwoven having abasis weight of about 20 to about 80 gsm and particularly about 28 to 60gsm. The floor sheet (14) may be hydrophobic and made of syntheticfibers. A suitable floor sheet (14) is a 60 gsm PE/PP discrete aperturedspunbond nonwoven available as SofSpan from Fitsea of Simpsonville, S.C.The floor sheet (14) may have a contact angle of 101 to 180 degrees withwater.

The floor sheet (14) may comprise a smoothing strip (12). The smoothingstrip (12) may have a width less than the floor sheet (14) and maycomprise at least about 10, 20, 30, 40, 50, 60 or 70% of the floor sheet(14) width. The smoothing strip (12) may have a width of at least 10,20, 30, 40, 50, 100, 150, 200, 250, mm and less than 70, 80, 100, 200 or300 mm, with a width of 24 to 44 mm being suitable and a width of 34 mmbeing preferred.

The smoothing strip (12) may be hydrophilic. As used herein hydrophilicmeans having a contact angle of 0 to 100 degrees, as measured by thetest method set forth herein. The smoothing strip (12) may particularlyhave a contact angle of 30 to 100 degrees and more particularly 55 to 90degrees. The smoothing strip (12) may comprise at least 50% cellulosiccontent to be hydrophilic.

More particularly, a suitable smoothing strip (12) may comprise alaminate of cellulose fibers and synthetic fibers. Such a laminate isbelieved to be helpful in attaining the performance of the cleaning pads(10) described herein. The cellulose fiber lamina may be outwardlyfacing, to provide friction and absorbency on the floor. The syntheticfiber layer may be postioned on contacting relationship with the floorsheet (14) to provide integrity during use.

A 23 gsm tissue and 17 gsm polypropylene spunbond hydroentagled, sold as40 gsm Genesis tissue by Suominen of Helsinki, Finland has been found tobe a suitable smoothing strip (12). Another suitable smoothing strip(12) may comprise 28 gsm tissue and 17 gsm polypropylene spunbondhydroentagled, sold as 45 gsm Hydratexture tissue by Suominen.

Cleaning pads (10) made with these smoothing strips (12) arerespectively referred to as Genesis and Hydra [for Hydratexture] in allof FIGS. 3 and 4. The smoothing strips (12) were all disposed on therespective floor sheets (14) with the tissue facing outwardly andpolypropylene disposed directly on the floor sheet (14).

The smoothing strip (12) may have a surface texture less than 0.5 mm,0.4 mm or less than 0.3 mm and even be essentially 0 mm Surface textureis measured as the peak to valley distance, independent of the smoothingstrip (12) thickness. A surface texture of less than 0.5 mm is believedto minimize streaking during cleaning, particularly when the floor driesand more particularly when a dark floor dries.

If desired, the smoothing strip (12) may have a color which contrastswith that of the floor sheet (14). This arrangement provides the benefitof a signal to the consumer that the smoothing strip (12) and floorsheet (14) have different functionalities.

Referring to all of FIGS. 3A-4F, inclusive, representative cleaning pads(10) are tested for both absorbency and kinetic coefficient of friction,using the respective test methods described herein. Commerciallyavailable cleaning pads (10) include those purchased from or under thenames of Dollar General, Grime Boss, Great Value, Kroger, Lola, PriceFirst, Rite Aid, Swiffer and Target, it being understood thatcommercially available products may change over time.

Four cleaning pads (10) according to the present invention were alsotested. Two of these cleaning pads (10) used the aforementioned 34 mmGenesis smoothing strip (12). Two of these cleaning pads (10) used theaforementioned 34 mm Hydra smoothing strip (12). All four of thecleaning pads (10) according to the present invention utilized anabsorbent core (16) having two airlaid layers (16U), (16L) of celluloseand AGM (16A), a floor sheet (14) and a back sheet (18). The twocleaning pads (10) labelled ‘Grad’ used a gradient core (16). The uppercore layer (16U) is the core layer disposed closer to and juxtaposedwith the back sheet (18). The lower core layer (16L) may be closer toand juxtaposed with the floor sheet (14). One of skill will recognizethat juxtaposition includes contacting the adjacent component. Pads madefor test purposes and not having AGM (16A) in the absorbent core (16) ora smoothing strip (12) are labelled ‘NO AGM’ and ‘No Strip,’respectively. The specific materials used in the cleaning pads (10)representing the four data points described and claimed herein are setforth in Table 1 below.

TABLE 1 Compo- Grad nent Genesis Hydra Genesis Grad Hydra Smooth-Genesis - Hydratexture - Genesis - Hydratexture - ing 40 gsm Hy- 45 gsmHy- 40 gsm Hy- 45 gsm Hy- Strip droentangled droentangled droentangleddroentangled (12) Laminate -- Laminate -- Laminate -- Laminate -- 23 gsmPulp/ 28 gsm Pulp/ 23 gsm Pulp/ 28 gsm Pulp/ 17 gsm 17 gsm 17 gsm 17 gsmSpunbond Spunbond Spunbond Spunbond Floor 60 gsm 60 gsm 60 gsm 60 gsmSheet Spunbond Spunbond Spunbond Spunbond (14) PP/PE PP/PE PP/PE PP/PEBlend - Blend - Blend - Blend - Apertured Apertured Apertured AperturedLower 150 gsm 150 gsm 150 gsm 150 gsm Core Airlaid - Airlaid - Airlaid -Airlaid - Layer 15% AGM, 15% AGM, 15% AGM, 15% AGM, (16L) 29% PE/ 29%PE/ 29% PE/ 29% PE/ PET fiber, PET fiber, PET fiber, PET fiber, 56% pulp56% pulp 56% pulp 56% pulp Upper 150 gsm 150 gsm 310 gsm 310 gsm CoreAirlaid - Airlaid - Gradient Gradient Layer 25% AGM, 25% AGM, AirlaidAirlaid (16U) 12% PE/ 12% PE/ Gradient Gradient PET fiber, PET fiber,Core Core 63% pulp 63% pulp per Table 2 per Table 2 Back 21 gsm 21 gsm21 gsm 21 gsm Sheet PP/PE PP/PE PP/PE PP/PE (18) Film Film Film Film

The particular core (16) construction provides for a compound gradientdistribution of AGM (16A) within the core. The upper core layer (16U)has 35 w % AGM. The lower core layer (16L) has 15 w % AGM. A core (16)having two, or more core layers (16U), (16L) disposed in contactingrelationship may have an AGM (16A) gradient distribution whichincreases, as the floor sheet (14) is approached and decreases, as theback sheet (18) is approached. The AGM (16A) gradient may be monotonicor non-monotonic.

The upper core layer (16U) and/or lower core layer (16L) may have an AGM(16A) gradient distribution therein. Again, it is desired that the AGM(16A) distribution increase/decrease as set forth above within the corelayer (16L)(16U).

The upper core layer (16U) of the two cleaning pads (10) according tothe present invention and labelled ‘Grad’ described above has the AGM(16A) distribution set forth in Table 2 below. Particularly the uppercore layer (16U) comprises three strata within that particular layer(16U). The strata provide for a gradient AGM (16A) distribution withinthat layer (16U) and a compound AGM (16A) within the core (16).

TABLE 2 Strata w % Strata Towards Floor Sheet (14) andLower Core Layer(16L) (Latex Glue) 0.8 (Pulp) 13.2 (Bico Fiber) 4.4 Middle Strata (Pulp)20.6 (AGM) 13.9 Strata Towards Back Sheet (18) (Pulp) 20.6 (AGM) 20.9(Pulp) 5.5

In contrast, a commercially available Swiffer WetJet cleaning pad has anupper core layer (16U) and lower core layer (16L) with 15 w % and 25 w %AGM, respectively for a total of 20.5 w % AGM in the core (16). Thiscommercially available cleaning pad has coefficients of friction of 0.6with water and 0.5 with amine oxide cleaning solution.

If a gradient distribution within a core layer (16L)(16U) occurs, thatrespective layer is considered as a whole when determining whether theoverall core (16) has a gradient AGM (16A) distribution. Thus, theembodiment described and claimed herein has a gradient core (16) due tothe AGM (16A) distribution of 15% in the lower core layer (16L) and 35 w% in the upper core layer (16U). An AGM distribution of at least 15 w %,and preferably 20 w %, 25 w %, 30 w % or 40 w % is desired between thelower upper core layer (16U) and lower core layer (16L).

Referring to FIG. 3A, the inventors have recognized that, under testingwith deionized water, cleaning pads (10) exhibit a generally positivecorrelation between coefficient of friction and absorbency. Conceptuallytwo relatively straight lines may be drawn, one from WetJet Extra Powerto Grad Hydra and one from Great Value to No AGM+Hydra. Such correlationis unexpected in view of the prior art.

Referring to FIG. 3B, it can be seen that under testing with deionizedwater, cleaning pads (10) according to the present invention may have anabsorbency of at least 0.45, preferably at least 0.48, more preferablyat least 0.5, more preferably at least 0.55, more preferably at least0.6, more preferably at least 0.65, but less than 1.0, 0.9 or 0.8. Anabsorbency with water in this range is judged advantageous for cleaningpurposes, without requiring undue AGM (16A) levels and the associatedcosts and material handling challenges.

Referring to FIG. 3C, it can be seen that under testing with deionizedwater, cleaning pads (10) according to the present invention may havecoefficient of friction of at least 0.6 [current WetJet having acoefficient of friction of 0.6 with water], preferably at least 0.65,more preferably at least 0.7, but less than 0.9, and preferably lessthan 0.8. A coefficient of friction with water in this range is judgedadvantageous for cleaning purposes, without requiring undue cleaningeffort at greater friction levels or without skipping over dirt and notadequately cleaning the floor at lower friction levels.

Referring to FIG. 3D, it can be seen that under testing with deionizedwater, particularly desirable cleaning pads (10) according to thepresent invention may have a coefficient of friction of at least 0.4,more preferably at least 0.5, more preferably at least 0.6, morepreferably at least 0.65, more preferably at least 0.7, but less than0.9 or less than 0.8 and may further have an absorbency of at least0.45, preferably at least 0.48, more preferably at least 0.5, morepreferably at least 0.55, more preferably at least 0.6, more preferablyat least 0.65, but less than 1.0, 0.9 or 0.8. The performance of such acleaning pad (10) is represented by the shaded box of FIG. 3D.

To further investigate the performance of a cleaning pad (10) accordingto the present invention, the cleaning pads (10) were tested with anamine oxide cleaning solution, as described herein. It is believed thattesting with this amine oxide cleaning solution more accuratelyrepresents the cleaning performance of a cleaning pad (10) in use.

Referring to FIG. 4A, the inventors have recognized that, under testingwith amine oxide cleaning solution, cleaning pads (10) exhibit agenerally positive correlation between coefficient of friction andabsorbency. Conceptually three relatively straight lines may be drawn,one from WetJet Extra Power to Grad Genesis, one from Target II (2) toRite Aid, and one from Target I to Dollar General. All three lines havea generally similar slope and linear correlation. Such correlation isunexpected in view of the prior art.

Referring to FIG. 4B, it can be seen that under testing with amine oxidecleaning solution, cleaning pads (10) according to the present inventionmay have an absorbency with amine oxide cleaning solution of at least0.35, preferably at least 0.4, more preferably at least 0.45, morepreferably at least 0.5, more preferably at least 0.55, but less than0.9, 0.85 or 0.8. An absorbency with amine oxide cleaning solution inthis range is judged advantageous for cleaning purposes, withoutrequiring undue AGM (16A) levels and the associated costs and materialhandling challenges.

Referring to FIG. 4C, it can be seen that under testing with amine oxidecleaning solution, cleaning pads (10) according to the present inventionmay have a coefficient of friction of at least 0.5, preferably at least0.55, more preferably at least 0.6, more preferably at least 0.65, butless than 0.9, and more preferably less than 0.8 and more preferablyless than 0.75. A coefficient of friction with amine oxide cleaningsolution in this range is judged advantageous for cleaning purposes,without requiring undue cleaning effort at greater friction levels orwithout skipping over dirt and not adequately cleaning the floor atlower friction levels.

Referring to FIG. 4D, it can be seen that under testing with amine oxidecleaning solution, cleaning pads (10) according to the present inventionmay have an absorbency conforming to the inequality:

Absorbency>0.7*cof−0.14,

-   -   wherein 0.5<cof<0.85 and    -   absorbency<1,        and cof is the coefficient of friction.

Optionally 0.55<cof<0.8, or 0.6<cof<0.75.

absorbency<0.9 or <0.8 and the 0.7 multiplier of the coefficient offriction may be 0.75-0.8. Such inequality is unexpected in view of theprior art.

A cleaning pad (10) that conforms to this inequality is judgedadvantageous for cleaning purposes, without requiring undue AGM (16A)levels and the associated costs and material handling challenges andjudged advantageous without requiring undue cleaning effort at greaterfriction levels or without skipping over dirt and not adequatelycleaning the floor at lower friction levels, wherein: 0.5<cof<0.9,and/or 0.35<absorbency<0.60.

An absorbency with amine oxide cleaning solution in this range is judgedadvantageous for cleaning purposes, without requiring undue AGM (16A)levels and the associated costs and material handling challenges.

Referring to FIG. 4E, the unpredicted linear relationship of fourcleaning pad (10)s according to the present invention is illustrated.But utilizing this previously unknown relationship it is believed animproved cleaning pad (10) is provided.

Referring to FIG. 4F, a cleaning pad (10) according to the presentinvention may conform to the region of the graph illustrated between theupper and lower lines. Such a cleaning pad (10) may conform to theequation Absorbency=0.7*cof+/−0.1.

-   -   wherein 0.5<cof<0.9 and    -   absorbency<1,        and cof is the coefficient of friction.

Optionally 0.55<cof<0.75, absorbency<0.9 or <0.8 and the band about theline can be +/−0.05. Such equation is unexpected in view of the priorart.

Test Methods

Prior to any testing, each cleaning pad (10) is conditioned for at least24 hours in a controlled room at 20-25 degrees C. and 40-50% relativehumidity.

Surface Texture

The texture outwardly facing surface of the smoothing strip (12) ismeasured while the smoothing strip (12) is still attached to the balanceof the cleaning pad (10). The cleaning pad (10) is cut, parallel to thewidth dimension of the cleaning pad (10) using a sharp knife in a mannerthat is not injurious to the texture of the floor sheet (14) orsmoothing strip (12). The sample is viewed from the edge, so that across sectional view of the cut plane can be measured.

The surface texture topography of the smoothing strip (12) is determinedto the nearest 0.01 mm, by measuring a linear distance along an axisperpendicular to the floor-facing planar surface of the smoothing strip(12). The distance to be measured is the vertical span, perpendicular tothe plane of the smoothing strip (12), between the bottom of a valleyand the top of an adjacent peak, wherein both endpoints are located onthe floor-facing surface of the smoothing strip (12). Distances aremeasured using the Point to Point measurement function or equivalent.

This procedure is repeated for a total of n=1 measurements on each offive different cleaning pads (10). The five results are averaged todetermine the surface texture for the smoothing strip (12).

A suitable digital microscope for making the measurements is a NikonSMZ1500 with the Nikon TV Lens C-0.6×, having an Infinity 2 Camera fromLumenera Corporation of Ottawa, Canada. Suitable measurement softwareincludes INFINITY ANALYZE, Release 5.0.3 from Lumenera Corporation.

AGM Gradient

Prophetically Micro X-ray Computed Tomography [CT] may be used todetermine if the core (16), or a layer thereof, has a gradient AGM (16A)distribution. CT imaging reports the X-ray absorption of a sample inthree-dimensions. MicroCT scanner instruments use a cone beam X-raysource to irradiate the sample. The radiation is attenuated by thesample and a scintillator converts the transmitted X-ray radiation tolight and passes it into an array of detectors. X-ray attenuation islargely a function of the material density of the sample, so densermaterials require a higher energy to penetrate and appear brighter(higher attenuation), while void areas appear darker (lowerattenuation). Intensity differences in grey levels are used todistinguish between different structures in the sample, such assynthetic/cellulose fibers, AGM (16A) particles, voids, and non-voidareas. Two-dimensional (2D) projected images can be acquired fromdifferent angles as the sample is rotated, enabling the creation of adigital three-dimensional (3D) reconstruction image of the sample using3D imaging software. Resolution is a function of the instrumentcharacteristics, diameter of the field of view and the number ofprojections used. The dataset obtained of the sample is visualized andanalyzed via image processing software program(s) in order to measure 3Dstructures and intensities.

Absorbency

Absorbency is measured using the following equipment.

A floor mop having a weight of 2.2+/−0.2 kg without the cleaning pad(10) and having a handle (34) and head (32). The head (32) is connectedto the proximal end of the handle (34) by a ball and socket joint oruniversal joint.

Referring to FIG. 6, the head (32) is rectangular with dimensions of11.4 cm×27.3 cm, a 2 mm crown extending in the 27.3 cm direction and iscovered with a compliant surface, such as EVA on the floor side. Thehandle (34) has a straight section (34S) with a length of 108+/−2.5 cmfrom the center of the ball and socket or universal joint. The straightsection (34S) of the handle (34) has a grip (34G) at the distal endthereof, the grip (34G) being oriented at 45+/−5 degrees to the straightsection (34S). The center of the grip (34G), as grasped by a typicaluser, is 5+/−2 cm from the transition between the straight section (34S)and grip (34G). A Swiffer WetJet (30) mop currently sold by the instantassignee, is suitable.

A metronome set at 70 beats per minute.

An mahogany plank engineered hardwood floor having dimensions of 122cm×91 cm with an aluminum oxide polyurethane coating and contact angleof 100+/−15 degrees with deionized water. Each plank is 12.1 cm widewith a 1 mm gap between adjacent planks. The floor has a 60 degree glossreading of 85+/−5 Gloss Units. The boards are aligned parallel to theshort direction, so that each board is at least 91 cm long extendingthat length without a seam. A Home Legend Santos Mahogany EngineeredHardwood floor, UPC 664646301473, has been found suitable.

-   -   A tared bottle of the liquid to be tested.    -   A hand-held trigger sprayer which sprays approximately 1.24        grams per stroke.    -   A scale accurate to 0.01 grams, as available from Mettler        Toledo.    -   1300 grams of dionized water.    -   1300 grams of solution comprising 0.04% amine oxide active        (C10-16 Alkyldimethyl) CAS no. 70592-80-2, 0.5% EtOH ethyl        alcohol and balance deionized water. This solution is        hereinthroughout referred to as an amine oxide cleaning        solution, and is representative of common, commercially        available cleaning solutions.    -   80/20 dionized water/isopropyl alcohol solution.

The floor is cleaned before each trial with the 80/20 water/IPA solutionand dried with paper towels. A sample cleaning pad (10) is weighed todetermine the initial weight using the scale.

Referring to FIG. 5, the floor may be conceptually divided into a 4×3grid of 12 squares, with each square being 30.5 cm×30.5 cm. Deionizedwater is sprayed onto the test surface in the respective centers of thefour squares spaced as shown with the stars, so that an unevendistribution of the water occurs. Approximately 2.75 to 3 grams of wateris sprayed onto each square indicated in FIG. 5 for a total of 11 to 12grams of water on the test surface. The spray bottle is reweighed todetermine the amount of liquid sprayed onto the floor.

The cleaning pad (10) is attached to the mop. If the cleaning pad (10)is larger than the head (32), the cleaning pad (10) is centered andtrimmed to fit, so that an edge of the cleaning pad (10) does not foldor improperly drag during testing. If a smaller cleaning pad (10) isused, the cleaning pad (10) is centered on the head (32).

The metronome is actuated. The mop is stroked forward and backwards sixstrokes in each direction for a total of 12 strokes to cover the entirefloor from left to right as shown in FIG. 5. The test is conducted usingordinary mopping force as applied through the mop handle (34) for theprescribed mopping rate, with no intentional compressive force added orsubtracted by the user, so that the total weight on the floor remains2.2+/−0.5 kg. The 12 strokes are repeated in reverse from right to left,to return to the starting point to complete one trial. The test userdoes not step on the test surface during any portion of the 12 strokes,but moves left to right as occurs under ordinary mopping conditions.

Mopping occurs at the rate of 70 strokes per minute, using themetronome. Each beat of the metronome matches a stroke from forward tobackwards or vice versa, for 24 total beats during the strokes used tocomplete a single test. The cleaning pad (10) is reweighed to determinethe amount of liquid absorbed during mopping. The percentage of thewater absorbed by the cleaning pad (10) is determined by dividing theamount of water absorbed by the amount of water dosed onto the testfloor and converted to a decimal value.

This procedure is repeated for a total of n=13 trials for each cleaningpad (10) and the results averaged, with the floor being cleaned beforeeach new trial using the aforementioned 80/20 solution. A total of n=3cleaning pads (10) are tested. The results of the three cleaning pads(10) are averaged to obtain the absorbency of that pad for deionizedwater. The absorbency is reported as a decimal, representing a fractionbetween and including 0 and 1.

This procedure, including the floor preparation, is repeated for theaforementioned amine oxide/ethyl alcohol solution. This solution,referred to herein as an amine oxide cleaning solution represents acommon type of commercially available cleaning solution for the testpurposes described and claimed herein.

Coefficient of Friction

The coefficient of friction of a material is the resistive force offriction divided by the normal or perpendicular force pushing thematerial against a surface. The coefficient of friction test method usesa Friction/Peel Tensile Tester, Model Insight 10 from MTS SystemCorporation of Eden Prairie, Minn. to measure the kinetic coefficient offriction.

A 203 g sled, with dimensions of 6.5 cm×11.0 cm×1.5 cm and having hookfasteners on the bottom surface is provided. A first sample of thecleaning pad (10) is attached to the sled using the hooks. If thecleaning is larger than the sled, the cleaning pad (10) is centered andtrimmed to fit, so that an edge of the cleaning pad (10) does not foldduring testing. If a smaller cleaning pad (10) is used, the cleaning pad(10) is centered on the sled. The pressure of the sled is about 2.84g/cm². This pressure simulates the typical pressure applied to acleaning pad (10) by a lightweight mop while a user is cleaning a floor.

The test surface is a glass plate 15 cm wide×28 cm long×5 mm thick,available from MTS System Corporation as part of Friction Testapparatus, part no. 100087526. The sled and test surface are cleanedusing the aforementioned 80/20 IPA/water solution. The instrument is setup as follows:

-   -   1. Set the “Sled Weight” to 203 g.    -   2. Set the “Data Acq. Rate” to 20 Hz.    -   3. Set the “Begin Point” to 10 mm    -   4. Set the “End Point” to 130 mm    -   5. Set the “Extension Limit High” to 135 mm    -   6. Set the “Crosshead” speed to 1000 mm/min    -   7. “Return” the load cell to the starting point for test.    -   8. Place the first sample and sled on top of the glass plate at        about 5 mm from back edge of the glass test surface such that        the sled is lined up at the center of the path where the hook on        the sled lines up with the eyelet of the load cell.    -   9. Attach the sled to the load cell by passing a string through        the pulley and up to the clamp on the test apparatus. Close the        clamp on the string to secure it.    -   10. Add 0.5 ml of test solution to the glass plate using a        volumetric pipette 1 cm in front of the sample. The test        solution should be applied to an area of about 50 mm in width        (the width being defined as the dimension perpendicular to the        direction of the sled) by 20 mm in length (the length being        defined as the dimension parallel to the direction of the sled        in motion) The same test solution is used for both the        absorbency test and the coefficient of friction test. That        absorbency and coefficient of friction are either both tested        with water or both tested with the amine oxide cleaning solution        described herein.    -   11. Initiate test by pressing the “play” icon. The load cell        starts moving from the back to the front dragging the sled and        the test sample.    -   12. When the test is complete, the load cell stops and the        program will display the measure of the Static Coefficient of        Friction (ST) as well as the Kinetic Coefficient of Friction        (KI). Record the Kinetic Coefficient of Friction measurement.        Activate the “Return” button so that the sled with the sample        returns to the starting position. Position the sled in the        starting position. Then press the play icon in order to repeat        the test.    -   13. Again when the test is completed, the load cell stops and        the program will display the Kinetic Coefficient of friction.        Record this measurement.    -   14. Again activate the Return button to send the sled back to        the start position.    -   15. Repeat test by positioning the sled with test sample at back        edge as previously discussed.    -   16. Each sample is tested three times. The test surface is not        re-wetted for the second and third trials.    -   17. Calculate the average of these 3 measurements    -   18. Repeat this procedure for n=3 samples and average the        results.

Static Contact Angle

The cleaning pad (10) is tested with the floor sheet (14) facingupwardly, so that the floor sheet (14) and smoothing strip (12), areexposed. The back sheet (18) is placed on a flat, horizontal surface.The area of test sample (i.e., floor sheet (14) or smoothing strip (12))is sufficient to prevent spreading of the test drop to the edge of thesample being tested or drops from contacting each other. The sample testsurface is not directly touched during preparation or testing, to avoidfinger contamination.

A contact angle goniometer is used to measure the static contact angleof the floor sheet and/or smoothing strip. The method describedhereinbelow is derived from ASTM D5946-09.

The apparatus for measuring contact angle has: (1) a liquid dispensercapable of suspending a sessile drop, as specified, from the tip of thedispenser, (2) a sample holder that allows a sample to lay flat withoutunintended wrinkles or distortions, and hold the sample so that thesurface being measured is horizontal, (3) provision for bringing thesample and suspended droplet towards each other in a controlled mannerto accomplish droplet transfer onto the test surface, and (4) means forcapturing a profile image of the drop with minimal distortion. A 5degree lookdown angle is used, so that the line of sight is raised 5degrees from the horizontal and the baseline of the drop is clearlyvisible when in contact with the sample. The apparatus has means fordirect angle measurements, such as image analysis of the drop dimensionsand position on the sample. A FTÅ200 dynamic contact angle video systemanalyzer manufactured by First Ten Angstroms, Portsmouth, Va. has beenfound suitable. FTÅ software supplied by First Ten Angstroms (Build 362,Version 2.1) has been found suitable. Lighting is adjusted so a clearimage is resolvable by the software, to extract the baseline and dropletcontour without user input.

A test sample is placed onto the specimen holder of the instrumentensuring that the sample is lying flat without unintended wrinkles ordistortions. A single droplet of 6.5+/−1.5 μL of deionized water istransferred by contact from a 22 gauge syringe needle dispenser onto thesurface of the sample, i.e. the floor sheet (14) or smoothing strip(12), as the case may be. Images of the profile of the drop arecollected by the software at a rate of at least 20 images/s. The contactangle between the droplet and the test surface is measured, in degrees,when the sessile volume has decreased by 2% of the initial volume. If a2% decrease in sessile volume does not occur, as for example may happenif the test sample is not absorbent, the contact angle is measured atequilibrium, as determined by lack of additional wetting and lack ofmovement of the droplet.

The test sample is moved, in order to place the next droplet onto aclean, undisturbed area of the sample, preferably at least 25 mm awayfrom any previous measurements. The test is repeated for a total of n=5samples. The measurements are checked to see if the measurements vary bymore than 5 degrees from the minimum reading to the maximum reading. Ifthe results of n=5 tests do not vary by more than 5 degrees, and the n=5results are averaged to yield the static contact angle.

If the readings vary by more than 5 degrees, then a total of n=20readings are taken and the results averaged. The n=20 average is thenused.

Implement (30)

The cleaning pad (10) according to the present invention may be used byhand or with a cleaning implement (30). Referring to FIG. 6, thecleaning implement (30) may comprise a plastic head (32) for holding thecleaning pad (10) and an elongate handle (34) articulably connectedthereto. The handle (34) may comprise a metal or plastic tube or solidrod.

The head (32) may have a downwardly facing surface, to which thecleaning pad (10) may be attached. The downwardly facing surface may begenerally flat, or slightly convex. The head (32) may further have anupwardly facing surface. The upwardly facing surface may have auniversal joint to facilitate connection of the elongate handle (34) tothe head (32).

A hook and loop system may be used to attach the cleaning pad (10)directly to the bottom of the head. Alternatively, the upwardly facingsurface may further comprise a mechanism, such as resilient grippers,for removably attaching the cleaning pad (10) to the implement (30). Ifgrippers are used with the cleaning implement (30), the grippers may bemade according to commonly assigned U.S. Pat. Nos. 6,305,046; 6,484,346;6,651,290 and/or D487,173.

The cleaning implement (30) may further comprise a reservoir for storageof cleaning solution. The reservoir may be replaced when the cleaningsolution is depleted and/or refilled as desired. The reservoir may bedisposed on the head (32) or the handle (34) of the cleaning implement(30). The neck of the reservoir may be offset per commonly assigned U.S.Pat. No. 6,390,335. The cleaning solution contained therein may be madeaccording to the teachings of commonly assigned U.S. Pat. No. 6,814,088.

The cleaning implement (30) may further comprise a pump for dispensingcleaning solution from the reservoir onto the target surface, such as afloor. The pump may be battery powered or operated by line voltage.Alternatively, the cleaning solution may be dispensed by gravity flow.The cleaning solution may be sprayed through one or more nozzles toprovide for distribution of the cleaning solution onto the targetsurface in an efficacious pattern.

If a replaceable reservoir is utilized, the replaceable reservoir may beinverted to provide for gravity flow of the cleaning solution. Or thecleaning solution may be pumped to the dispensing nozzles. The reservoirmay be a bottle, and may be made of plastic, such as a polyolefin. Thecleaning implement (30) may have a sleeve (36), which removably receivesthe bottle, or other reservoir. The cleaning implement (30) may have aneedle, optionally disposed in the sleeve (36) to receive the cleaningsolution from the bottle. The bottle may have a needle piercablemembrane, complementary to the needle, and which is resealed to preventundesired dripping of the cleaning solution during insertion and removalof the replaceable reservoir. Alternatively or additionally, If desired,the implement (30) may also provide for steam to be delivered to thecleaning pad (10) and/or to the floor or other target surface.

A suitable reservoir of cleaning solution and fitment therefor may bemade according to the teachings of commonly assigned U.S. Pat. Nos.6,386,392, 7,172,099; D388,705; D484,804; D485,178. A suitable cleaningimplement (30) may be made according to the teachings of commonlyassigned U.S. Pat. Nos. 5,888,006; 5,960,508; 5,988,920; 6,045,622;6,101,661; 6,142,750; 6,579,023; 6,601,261; 6,722,806; 6,766,552;D477,701 and/or D487,174. A steam implement (30) may be made accordingto the teachings of jointly assigned 2013/0319463.

The dimensions and values disclosed herein are not to be understood asbeing strictly limited to the exact numerical values recited. Instead,unless otherwise specified, each such dimension is intended to mean boththe recited value and a functionally equivalent range surrounding thatvalue. For example, a dimension disclosed as “40 mm” is intended to mean“about 40 mm” whether or not the term ‘about’ is expressly recited.Every range disclosed herein includes all endpoints of that rangewhether disclosed within that range or as part of a related range. Thustwo endpoints of the same range may be disclosed as endpoints of broaderor narrower ranges. The common mathematical symbols > and < mean greaterthan or equal to and less than or equal to, respectively, and includethe endpoints set forth in the equations and inequalities below.

Every document cited herein, including any cross referenced or relatedpatent or application, is hereby incorporated herein by reference in itsentirety unless expressly excluded or otherwise limited. The citation ofany document is not an admission that it is prior art with respect toany invention disclosed or claimed herein or that it alone, or in anycombination with any other reference or references, teaches, suggests ordiscloses any such invention. Further, to the extent that any meaning ordefinition of a term in this document conflicts with any meaning ordefinition of the same term in a document incorporated by reference, themeaning or definition assigned to that term in this document shallgovern.

While particular embodiments of the present invention have beenillustrated and described, it would be obvious to those skilled in theart that various other changes and modifications can be made withoutdeparting from the spirit and scope of the invention. It is thereforeintended to cover in the appended claims all such changes andmodifications that are within the scope of this invention.

What is claimed is:
 1. A cleaning pad comprising: a liquid pervioushydrophobic floor sheet having an inwardly facing surface and anoutwardly facing surface opposed thereto, an absorbent core juxtaposedwith said inwardly facing surface of said floor sheet and comprisingabsorbent gelling material, and a smoothing strip joined to saidoutwardly facing surface of said floor sheet, said smoothing striphaving a width of 13 mm to 100 mm, said smoothing strip comprising acellulose fiber lamina and a synthetic fiber lamina joined in alaminate, said cellulose fiber lamina facing outwardly from saidcleaning pad and said synthetic fiber lamina being in contactingrelationship with said floor sheet.
 2. A cleaning pad according to claim1 wherein said smoothing strip has a surface texture of less than 0.5mm.
 3. A cleaning pad according to claim 2 wherein said core comprisesat least two cellulose layers joined in fluid communication.
 4. Acleaning pad according to claim 3 comprising 5 to 50 w % AGM.
 5. Acleaning pad according to claim 4 wherein said smoothing strip has acontact angle of 30 to 100 degrees.
 6. A cleaning pad according to claim5 wherein said outwardly facing surface of said floor sheet has acontact angle of 101 degrees to 180 degrees.
 7. A cleaning padcomprising: a liquid pervious hydrophobic floor sheet having an inwardlyfacing surface and an outwardly facing surface opposed thereto, anabsorbent core juxtaposed with said inwardly facing surface of saidfloor sheet and comprising 5 to 50 w % absorbent gelling material, and asmoothing strip joined to said outwardly facing surface of said floorsheet, said smoothing strip having a surface texture of less than 0.5 mmand a hydrophilic outwardly facing surface.
 8. A cleaning pad accordingto claim 7 wherein said smoothing strip has a contact angle of 55degrees to 90 degrees.
 9. A cleaning pad according to claim 8 whereinsaid outwardly facing surface of said floor sheet has comprises adiscrete apertured, hydrophobic nonwoven.
 10. A cleaning pad accordingto claim 8 further comprising a back sheet being joined to said coreopposite said floor sheet with said core therebetween, and wherein saidfloor sheet has a floor sheet width, and said smoothing strip has asmoothing strip width, said smoothing strip width being from 20 mm to 80mm.
 11. A cleaning pad according to claim 10 wherein said smoothingstrip comprises a laminate of cellulose fibers and synthetic fibers. 12.A cleaning pad according to claim 11 wherein said smoothing stripcomprises more than 50 weight percent cellulose fibers and a balance ofsynthetic fibers.
 13. A cleaning pad according to claim 12 wherein saidcore comprises two layers joined together, a first said layer beingjuxtaposed with said inwardly facing surface of said floor sheet and asecond said layer being juxtaposed with said back sheet, said secondlayer having a greater w % AGM than said first layer.
 14. A cleaning padaccording to claim 13 wherein said AGM in said second layer isstratified to provide a gradient distribution therein.
 15. A cleaningpad comprising: a liquid pervious hydrophobic floor sheet having aninwardly facing surface and an outwardly facing surface opposed thereto,a liquid pervious backsheet peripherally joined to said floor sheet, anabsorbent core intermediate said floor sheet and said back sheet, saidabsorbent core comprising 10 w % to 45 w % absorbent gelling materialdisposed in a gradient with the percentage AGM increasing as saidbacksheet is approached, and a hydrophilic smoothing strip joined tosaid outwardly facing surface of said floor sheet, said strip having acontact angle of 0 degrees to 100 degrees.
 16. A cleaning pad accordingto claim 15 wherein said absorbent core comprises two core layers influid communication, including a first cellulosic layer juxtaposed withsaid floor sheet and a second cellulosic layer juxtaposed with said backsheet.
 17. A cleaning pad according to claim 16 wherein said first corelayer comprises 10 to 20 w % AGM.
 18. A cleaning pad according to claim17 wherein said second core layer comprises at least 20 w % AGM.
 19. Acleaning pad according to claim 18 wherein said smoothing strip has asurface texture less than 0.5 mm.
 20. A cleaning pad according to claim19 wherein said smoothing strip has a surface texture less than 0.2 mm.